It is known to calculate separable two dimensional linear transforms on blocks of data elements for various purposes in digital signal processing. Such transforms may include discrete cosine transform (DCT) inverse discrete cosine transform, a low pass filter and identity. Discrete cosine transforms are particularly useful in image compression systems and may be used to limit the amount of data necessary for transmission and storage of video signals. The above mentioned transforms may be used to meet requirements of the CCITT Video Codec standard.
It is the object of the present invention to provide improved apparatus and methods for computing separable two dimensional linear transforms with improved circuitry which may permit more than one type of transform to be carried out on data passing through the circuitry. It is a further object of the invention to provide improved circuitry requiring a reduced number of transistors thereby providing benefits in the chip area required, cost and power dissipation.